1. Field of the Invention
The present invention relates to power supply circuits, and particularly to a power supply circuit for a motherboard in a computer.
2. Description of Related Art
In electronics and particularly in computer electronics, jumpers are typically used to set up or adjust printed circuit boards, such as the motherboards of computers. Jumper pins (points to be connected by the jumper) are arranged in groups called jumper blocks, each group having at least one pair of contact points and often more. In general, each contact in a jumper block terminates in a small metal pin. An appropriately sized conductive sleeve called a jumper, or more technically, a jumper shunt, is slipped over the pins to complete the circuit.
Jumper blocks and jumpers are often used on a motherboard to maintain power supply to a south bridge thus safeguarding CMOS information stored therein. Further, the jumpers may be moved to invoke a function to clear the CMOS information in the south bridge, and reset the BIOS configuration settings, which allows the computer to boot if a recent BIOS setting made it unable to boot, or if the CMOS boot password was forgotten. However, if the jumper falls off from the jumper blocks in the first case, a power supply circuit on the motherboard will not supply power to the south bridge, and the CMOS information in the south bridge may be lost.
What is needed, therefore, is to provide a power supply circuit for a motherboard which can avoid losing CMOS information in a south bridge thereof when a jumper falls off from a jumper block.